drive: add support for multipart document extensions
drive: add support for multipart document extensions

B4dM4n/rclone,B4dM4n/rclone,ncw/rclone,ncw/rclone,ncw/rclone,olihey/rclone,olihey/rclone,olihey/rclone,B4dM4n/rclone,B4dM4n/rclone,ncw/rclone,olihey/rclone